Sources close to the singer tell TMZ that Spears checked in because she was experiencing significant pain in one of her molars. She was seen leaving the hospital less than one hour later.

Larry Rudolph, says "She has had a toothache for a few days and her assistant got a dentist to see her on Sunday."

Last week, Spears stepped out in public for the first time since leaving Malibu's Promises treatment facility on March 20.

Spears and two of her girlfriends took a one-hour hip-hop class at Millennium Dance Complex in North Hollywood on Friday, March 23 reports US magazine.

"She was very excited to dance and was smiling and saying hi to everyone," one onlooker said to Usmagazine.com.

Later that evening, a blue-contact-lens sporting Spears and three girlfriends met up for a sushi dinner at trendy Japanese fusion joint SHU-Sushi House Unico in Bel Air.

"She was really cute and having a good time with her girlfriends," an eyewitness said to Usmagazine.com. "They were giggling at the table and making jokes."